Sustainable deployment of manure found to increase maize yield

During a multi-year study, Spanish researchers investigated the efficacy of substituting cow manure for chemical fertilizers in maize crop that was being grown in Mediterranean conditions. They found that manure-based fertilization could benefit both the yield of the crop and the quality of the soil.

The study was supported by the Universitat de Lleida. Its results were published in the European Journal of Agronomy.

The trial was held in a furrow-irrigated farm with sandy soil and dry Mediterranean weather. It lasted for a period of seven years.

At the start of each year, three different ratios (0, 30, and 60 Mg per hectare) of cattle manure were applied to different parts of the field. Furthermore, these natural fertilizers were combined with four different rates (0, 100, 200, and 300 kg/ha) of chemical fertilizers.

The highest average yield of maize grain during the trial period for the combination of cow manure fertilizer with mineral fertilizer was produced by the 30 Mg/ha rate. Without mineral fertilizer, it was the 60 Mg/ha rate. The best yields exceeded the maximum rates required by the EU.

The apparent nitrogen recovery fraction throughout the trial was 29 percent for the pure cattle manure. On average, the lower the cow manure ratio, the higher the mineral fertilizer required to compensate, which resulted in lower recovery of nitrogen.

With the 30 and 60 Mg/ha rate of cow manure, the nitrogen recovery rate went up. This was attributed to the leftover organic nitrogen from earlier growing seasons.

The researchers concluded that there was promise in using cow manure as a partial or full alternative to mineral fertilizer.